Risk factors and drug resistance of adult community-onset urinary tract infections caused by producing extended-spectrum β-lactamase in the Chongqing region, China: a retrospective case-control study.

Objective: To evaluate the prevalence, resistance and risk factors of community-onset urinary tract infections (COUTIs) caused by extended-spectrum β-lactamase-producing (ESBL-EC) for providing a basis for the selection of clinical therapeutic agents.

Design: A retrospective case-control study.

Setting: The Affiliated Dazu Hospital of Chongqing Medical University (also known as The People's Hospital of Dazu Chongqing), a 1000-bed tertiary hospital in China.

Data And Participants: This study encompassed adult patients diagnosed with community-acquired urinary tract infections (UTIs) caused by between May 2017 and December 2022 with exclusion criteria including incomplete clinical data, disagreement to participate in the study, hospitalisation duration exceeding 48 hours prior to confirmation of diagnosis and prior history of urinary tract infection caused by .

Outcome Measures: The risk factors for COUTIs caused by ESBL-EC were evaluated using a case-control design, defining patients who were diagnosed with UTIs and had an ESBL-positive urine culture as the case group and patients who were diagnosed with UTIs and had an ESBL-negative urine culture as the control group. Perform drug susceptibility testing and resistance analysis on isolated ESBL-EC.

Results: In total, 394 cases of COUTIs caused by were included; 192 cases were ESBL-positive with a detection rate of 48.7% (192/394). Parenchymal tumour, history of urolithiasis stone fragmentation, history of urological surgery, hospitalisation within 6 months, indwelling catheter outside the hospital and antibiotic use (mainly third-generation cephalosporins) were the factors significantly associated with COUTIs caused by ESBL-EC (p<0.05) through logistic regression for univariate analysis. Multivariate analysis revealed that a history of urolithiasis stone fragmentation (OR=2.450; 95% CI: 1.342 to 4.473; p=0.004), urological surgery (OR=3.102; 95% CI: 1.534 to 6.270; p=0.002), indwelling catheter outside hospital (OR=2.059; 95% CI: 1.025 to 4.133; p=0.042), hospitalisation within 6 months (OR=2.127; 95% CI: 1.207 to 3.748; p=0.009) and use of third-generation cephalosporins (OR=1.903; 95% CI: 1.069 to 3.389; p=0.029) were the independent risk factors for COUTIs caused by ESBL-EC. The results of the drug susceptibility testing revealed that ESBL-EC exhibited the highest resistance rates to ampicillin, ceftriaxone and cefixime, all at 100%. Mezlocillin followed with a resistance rate of 98.7%. On the other hand, ESBL-EC strains displayed the highest sensitivity to carbapenem antibiotics (imipenem, meropenem, ertapenem) and amikacin, all at 100%. Sensitivity rates were also high for cefotetan at 96.6%, piperacillin/tazobactam at 95.3% and nitrofurantoin at 87.9%.

Conclusions: Our results revealed high ESBL-EC detection rates. COUTIs caused by ESBL-EC are more likely to occur in patients with parenchymal tumour, a history of urolithiasis stone fragmentation, a history of urological surgery, hospitalisation within 6 months, indwelling catheter outside the hospital and use of third-generation cephalosporins. These patients were highly resistant to penicillins, cephalosporins and quinolones.